The Department of Water and Sanitation (DWS) has used a “sledgehammer” for its R1bn treatment plant for acid mine drainage (AMD) on the Eastern mining basin that could ultimately create more toxic water.
This is the view of water strategy and consulting mining hydrologist Kym Morton, who believes government is “wasting money” by pumping large volumes of water and adding lime that makes it alkaline but still toxic and hazardous.
“This is a sledgehammer approach to what can be solved by accurate monitoring and treatment of real AMD seepage at each decant point,”she says.
Last week the DWS, through the Trans-Caledon Tunnel Authority launched the treatment plant in Spring, the largest of its kind in the world, to counter the impact of 120 years of mining in the Witwatersrand basins.
The plant is part of the short-term solution to halt the breaching of the environmental critical level in the Central and Eastern mining basins.
Every day the TCTA pumps about 110million litres of water to mitigate against the pollution of underground water sources into the Blesbokspruit and the wetlands that then drain into the Vaal river system.
But Morton says this draws down the level in the mine shaft to 120 m below the surface, exposing more pyrite to oxygen.
This process could create more AMD, which us caused when oxygen and water come into contact with pyrites in exposed rock, sludge or tailings.
“The pumping is therefore increasing the creation of AMD…..the DWS claims they’ve had a huge success in treating the water pumped from the shaft.
“The reality is they are not treating the water to a better state. All that is achieved is using expensive and scarce lime to increase the pH of the water from 3 to between 7,2 and 9.2. The water leaving the pumping site is not drinkable, is hazardous to animals, humans, aquatic species and plants. And because the pH has been altered, the metals in the water precipitate out as a sludge.
“Unless the sledge is sealed from rain water, surface water runoff and ground water, the toxic elements will be mobilised and enter the water system.”
“A better solution is to treat the water at source and remove both the metals and the sulphates for resale.”
Philip de Jager, an attorney who represents communities in Springs agress.
“What is of particular concern is that the sludge will be stored at the existing slimes dam situated next to the Blesbokspruit, and too close for comfort to the suburb of Strubenvale in Springs.
“We’re concerned about the possibility of flooding, which will have a negative impact on downstream property owners, including Marievale Bird Sanctuary.”
Professor Frank Winde of the mine research group at North West University says: “It’s not only that the capital layout is significant; it is also the running costs for pumping the water from depth, adding the chemicals and disposing of the sludge, especially as it needs to be done indefinitely. All of this with little to show as the discharged water is still largely unusable and the generates sludge may pollute other resources”.
His colleague, Ewald Erasmus, argues that if incentives were given to mining companies to remove uranium, the sulphates and as many other metal contaminants as economically possible, the “many will benefit, and not just a few”.
[An extract from the article’